The invention relates to a method for producing a punching tool, particularly to a method for producing one to the top of which a tungsten carbide piece is attached.
Nowadays, punching tools can be categorized into two types. One is made of tungsten carbide which has a high manufacturing cost and which is brittle by nature, which results in frequent tool breakage in use. As shown in FIG. 1, the other type of punching tool includes a punch rod 4 and a tungsten carbide rod 3 having more than a third of the length thereof inserted into a well-matched corresponding hole provided on the punch rod 4 with a brazing material 34 joining them together. The latter type is an improvement over the former type; however, it still suffers from the following disadvantages:
1. It requires that the tungsten rod 3 have a suitable length in order that the rods 3 and 4 can be effectively joined together. PA0 2. It is necessary to accurately work the corresponding hole for tightly fitting the tungsten carbide rod therein so that the punching tool can be durable. Nevertheless, such a punching tool still does not have sufficient strength and necessitates frequent replacement which, in turn, inevitably reduces efficiency. PA0 3. Owing to the difference in material, the carbide rod 3 is broken easily where it joins the peripheral portion of the bottom of the corresponding hole because of stress concentration.